PURIFICATION OF FUMONISIN B-2 ISOLATED FROM RICE CULTURE

Procedures are presented for the production, isolation, and purificati on of the mycotoxin fumonisin B-2 from cultures of Fusarium moniliform MRC 826 grown on rice. Fumonisins B-1, B-2, and B-3 were extracted wi th acetonitrile:water, and the extracts were filtered and reduced in v olume with a rotary evaporator. Fumonisin B-2 was isolated from the ot her fumonisins B-1 and B-3 by preparative reversed-phase Liquid chroma tography(LC). Fractions that contained fumonisin B-2 were concentrated to remove acetonitrile, and the remaining water fraction was frozen a nd freeze dried. The freeze-dried material was dissolved in a minimum amount of methanol and separated by preparative, centrifugally acceler ated, radial, thin-layer chromatography on a silica gel-coated plate. An applicator that precisely controlled the rate of application of ext ract to the sorbent material was used to minimize the width of the ban d of extract. Fractions were eluted from the spinning plate with a lin ear gradient of (A) chloroform:acetone (4:3) and (B) methanol:acetone (1:1) applied at a rate of 3 mL/min. Gradient starting conditions were 10% B and 90% A, and ending conditions were 50% A and B. Fractions th at contained fumonisin B-2 were combined and freeze dried. Recovery of purified fumonisin B(?)2 was 90% of that of the starting extract, and purity as determined by HPLC light scattering detection was greater t han 90%.